- Are you restricted by current contract, location or desire to a certain carrier or carriers?
- Will this be your only mobile device or will you also own some type of tablet?
- Do you want or require a specific operating system - Apple, Android, etc.?
- Is compatibility with some other device important?
Once you answer these questions you will be in a much better position to begin your search and say something more intelligent than "I think I like the blue one".